The objective of this proposal is to utilize magnetic source imaging (MSI) to evaluate the organization of brain functions in children with spina bifida (SB). Children with SB sustain a congenital insult to the brain that begins in the first trimester and results in hydrocephalus that is usually treated at birth. It is well-established that many children with SB have unusual profiles of cognitive ability, with strengths in word reading, math facts, and object-based visual perception in the face of difficulties with reading comprehension, math procedures, and many aspects of action-based visual perception, attention, and motor function. What is unclear is how the SB brain mediates these functions and the extent to which variations within the SB group reflect differences in cerebral reorganization. In this proposal, we propose systematic explorations of functional organization of key motor, somatosensory, language, and cognitive skills that characterize the modal profile associated with SB in a sample of 136 children with SB, 20 with aqueductal stenosis (AS), and 60 controls. Four specific aims are proposed, each representing a separate experiment. Aim 1 (Motor, somatosensory, and language mapping) attempts to identify the brain activation profiles indicative of the neuronal mechanisms that mediate basic somatosensory and motor functions of the upper extremities as well as receptive language function among 136 SB children and 60 controls. Aim 2 (Reading and arithmetic) addresses the representation of reading and math skills in 60 children with SB who vary in these skills. Aim 3 (Visual attention) addresses the role of the parietal lobe in mediating visual attention skills using a line bisection task in 40 children with SB divided according to whether they show or do not show a leftward bias on a horizontal line bisection task in Project 3, and 20 controls. Aim 4 (Rhythm discrimination) uses a rhythm perception task to assess cerebellar function in 20 children with SB characterized by early hydrocephalus and a congenital cerebellar malformation, 20 with AS characterized by early hydrocephalus, but no cerebellar malformation, and 20 controls. The results should help establish how the congenitally malformed brain reorganizes function as well as help establish the basis for the neurological mechanisms by which these functions are mediated in children with SB.